The Mauritian government hopes that fewer bats on the island will help reduce damages to mango and litchi fruits in orchards, and boost revenue for fruit farmers.
Conservationists say this decision to cull is not backed by scientific evidence, may drive the species to Endangered status, and is “unacceptable.”
Culling bats when they are pregnant or suckling babies is also unethical and inhumane, conservationists say.
The government of Mauritius has announced its plans of culling 20 percent of the endemic and vulnerable Mauritius fruit bat (Pteropus niger) population on the island. The government hopes that fewer bats will help reduce damages to fruits like mangoes and litchis in orchards and boost revenue for fruit farmers.
The culling will start mid-October and will go on for three weeks until the “target is attained,” Mahen Kumar Seeruttun, Minister of Agro-Industry and Food Security, said at the sixth National Assembly of the Mauritian Parliament held on October 6.
But conservationists are calling this decision “unacceptable” and “disgraceful.”
“Culling is the most insensible, unscientific action that can be taken at this stage, as it will, at a cost, harm both the fruit producers and the native threatened biodiversity of the country,” Vincent Florens, Associate Professor of Ecology at the University of Mauritius, told Mongabay.
The cull could be disastrous for the native bat species, the International Union for Conservation of Nature (IUCN) added in a statement.
“The implementation of a cull will very likely result in an up-listing of the species from Vulnerable to Endangered or Critically Endangered on the IUCN Red List, which will damage the reputation of Mauritius as a world leader on conservation,” the statement notes.
Is the cull based on scientific evidence?
In 2013, the National Parks and Conservation Service (NPCS) of Mauritius estimated that there were around 90,000 Mauritius fruit bats on the island. These numbers, according to Seeruttun, indicate that bats have gone from being “endangered” to “being a pest.”
To control their population, the government plans to cull 20 percent of the bats, or 18,000 individuals in the coming weeks.
However, bat experts say that the methods used to estimate bat populations have been flawed, and the portion of the species killed off in the culls could be significantly higher than 20 percent. They warn a cull based on these inaccurate numbers could be catastrophic for the native bat species.
According to Ryszard Oleksy, a doctoral student at the University of Bristol in the U.K., the bat number estimates are most likely based on double, if not triple, counting.
Oleksy, who has been monitoring bat movements in Mauritius, has found that the fruit bats move long distances all over the island. “They can change the roost every night and very often they fly from one side of the island to another within one night,” he said. “The NPCS survey was done over longer period of time, therefore the same bats could have been counted in the north of the island as well as in the south a few weeks later.”
So conservationists believe that the 90,000 figure is an over-estimate. However, the degree of overestimation is difficult to ascertain because reports are not available, Florens said.
Moreover, “a number of officers who took part in those population estimates themselves now acknowledge this overestimation problem,” he added.
Instead, many conservationists estimate that there are possibly around 50,000 Mauritius fruit bats on the island.
If this is indeed the case, then culling 18,000 bats would result in the killing of 36 percent of the fruit bat population.
“On top of that people shoot bats illegally in Mauritius,” Vikash Tatayah, Conservation Director of Mauritian Wildlife Foundation and member of the IUCN SSC bat specialist group, told Mongabay. “And there are bats that are electrocuted on electrical lines every year. So you add another couple of thousand bat deaths due to that, and you will see that the actual figure that we are talking about is getting alarmingly high. And the proportions are alarmingly high.”
How much damage do bats cause?
According to the government, bats are allegedly responsible for a large proportion of the damage – as high as over 70 percent — to fruits like mangoes and litchis in orchards. However, this assertion is not backed by scientific evidence, experts say.
“Where is the damage caused by birds, rats, monkeys, wind or fruit fly?,” Oleksy asked. “All these animals feed on commercial fruits.”
Preliminary results of Oleksy’s study show that bats seem to damage mostly larger trees that are more than six meters tall, and damage to shorter trees due to bats is minimal. Moreover, his results suggest that birds may be causing as much damage to fruits as bats.
In fact, his study has found that a larger proportion of fruits — around 20 percent — get damaged due to natural causes like wind or over-ripening, causing fruits to fall to the ground.
Still, bats are easier targets because they come at night, and farmers have little control over them, Oleksy said.
“They are also very noisy when feeding in groups, as they fight for the food and place on the tree,” he explained. “Sometimes only two bats on the same branch may make as much noise as 10. Thus, people may think they come in great numbers, eating all the fruits and leaving before it gets light and the damage can be seen.”
Bats play important ecosystem functions — they pollinate plants and disperse seeds. “I think not recognizing this is a failure of the plan,” Tatayah said.
Cull goes against animal welfare ethics
Conservationists say that the cull is also unethical and inhumane.
“The government has scheduled the culling at a time when many bats are either pregnant or carrying young suckling babies,” Tatayah said.
“So shooting bats at this time of the year will mean that lots of babies will die or will be wounded. Lots of babies will be abandoned. There might also be forced or induced abortion,” he said. “Presumably the cull will be done with a shotgun. So the bats will die a slow, painful death. Some bats don’t die from being shot and have to carry these pieces of bullets rest of their lives. So this is quite inhuman to be shooting bats now.”
Moreover, Mauritius does not have enough resources to take care of babies that get abandoned after their mothers are shot, Tatayah said. “If 18,000 bats are killed, we’re talking about hundreds of orphaned bats and we don’t have the capacity to take care of so many at the present resource level that Mauritius has.”
Protecting the bats
When contacted by Mongabay for details about how the government plans to conduct “controlled culling” of the bats, Agro-Industry minister Seeruttun said in an email, “I can reassure you that my government will do nothing to put at risk the very existence of fruit bat in Mauritius.”
However, conservation groups are not convinced, and want the cull to be called off immediately. An online petition to stop the cull has garnered nearly 5,000 supporters in a week.
In fact, a public perception survey of 560 Mauritians conducted by a graduate student from Nottingham Trent University found that over 80 percent respondents were neutral or positive towards bats.
“Clearly the decision to cull emanates from pressure based on exaggerations from farmers and/or industry,” Florens said. “It disregards the scientific evidence which is robustly in favor of conservationists.”
Culling is not the solution, according to experts. Instead, farmers need to adopt other measures to protect their orchards.
One measure is to keep tree height short, experts say. This can be achieved by either planting dwarf varieties of the fruit trees or by pruning the trees.
Placing nets around the trees will protect trees from not only bats but also introduced bird species like mynahs, bulbuls and parakeets, Florens said. Restoring native fruit habitats of the bats is critical too, he added.
If the cull is implemented despite the lack of evidence to back it up, the food production industry of Mauritius should label itself as “destructive to threatened species” and “non-environmental friendly,” Florens said.
“A campaign of information should then be made to label the Mauritius litchi and mango production as such and a call for the boycott of these products should be made locally but above all internationally particularly in the main countries importing these fruits to sensitize importers and consumers.”
Article published by Shreya Dasgupta on October 16, 2015.